(a) Field of the Invention
The present invention relates to an audio-separating apparatus and an operation method thereof, and more particularly to an audio-separating apparatus applying both blind signal separation (BSS) and noise reduction mechanisms and an operation method thereof.
(b) Description of the Prior Art
Various noises, such as echoes, reverberations and the like, are omnipresent in people's daily lives, and all such noises would cause interference with sound signals. When sound signals are interfered by an interference source, the quality of the sound signals will degrade. For the hearing impaired who use hearing aids or cochlear implant, it is extremely difficult to recognize the sounds to be heard in a noise-filled environment without noise reduction or noise separation. Therefore, more and more emphases have been gradually put on noise reduction algorithms based on digital signal processing to obtain clearer sounds.
In order to obtain clearer sounds, many noise reduction algorithms, such as independent component analysis (ICA), have been derived. The speech signals to be heard can be retrieved from a noise-filled environment by the algorithm to enhance the speech signals. In the prior art, the disclosure of US200713381 indicates that speech signals can be retrieved from a noise-filled environment via an ICA method. Nonetheless, conventional noise reduction algorithms and ICA still have some drawbacks. It is easy to lose portions of speech segments and produce musical noises during the processing in many conventional noise reduction methods. Such effect leads to reduced quality of speech; in other word, it is difficult to recognize speech signals. Furthermore, when ICA is used, at least two microphones are required to record sound signals. However, sound propagates at a substantially slower speed. If the microphones are placed at different positions, the time taken for a signal to be transferred from each sound source to each microphone is unequal. This causes the propagation delay between sampling points, referred to as the spatial aliasing effect. However, the spatial aliasing effect is not taken into consideration in the theoretical basis of ICA. Therefore, significant effect in the separation of sound signals by using ICA can not be well achieved.